Focal-plane shutters of curtain type



@Ct Wy E95@ A svaNssQN FQCALQLANE SHUTTERS oF CURTMN TYPE Filed Feb, 5 1948 INVENTQR.

Patented ct. 1K7,

FOCAL-PLANE SHUTTERS OF CURTAIN TYPE Algot Percy Svensson, Goteborg, Sweden, assignor to Fritz Victor Hasselblad, Goteborg, Sweden Application February 5, 1948, Serial No. 6,381 In Sweden June 16, 1944 3 Claims.

The present invention relates to camera shutters of curtain type and more particularly to shutters of said kind consisting of thin metal foils.

In shutters of this kind hitherto known the curtains consist of plane metal foils which, however, suffer from the disadvantage that they are subjected to uncontrolled folds at the great speeds occurring when using the camera which destroy the curtain.

The present invention has for its object to overcome this disadvantage and is broadly characterized in that the metal foil is corrugated at right angles to the direction of movement of the curtain.

By such a construction the forming of uncontrolled folds is prevented and, besides this, the corrugated curtain will show a certain elasticity in the direction of movement which contributes to an increase of the duration of the curtain.

An embodiment of the invention is illustrated in the accompanying drawing, wherein Figure 1 is a front elevation of a shutter curtain accordto the invention, and the device for winding up the curtain and its hangings, Figure 2 is a side elevation of the curtain and the winding up device, and Figures 3 and l are sections on. a larger scale through certain parts of the curtain along the line III- III and IV-IV, respectively.

In the drawing I denotes the rectangular curtain which consists of a thin foil of stainless steel. Sixteen thousandths of a millimetr-e has, by various tests, been found to be a suitable thickness for the foil, but thinner or thicker foils may be employed. The hangings of the curtain consist of metal foil bands 2 formed integrally with the curtain l. The curtain proper as well as the bands 2 are according to the invention corrugated at right angles to the direction of movement of the curtain, whereby uncontrolled folds are pre vented and the curtain and the bands will show a certain elasticity in the direction of movement nf the curtain. The corrugations may suitably be of wave form such as in the form of a sinewave, but other forms of corrugation may be employed. The edge portion of the curtain at the end remote from the bands 2 is inserted in an. axial slot or groove in a rotationally mounted roller 3 serving for the winding up of the curtain, and is fastened in said groove by pressing the sides of the groove towards each other. At the edge portion of the other end of the curtain from which extend the hangings 2 there is pressed on a metal rim 5, U-shaped in cross-section, the bottom portion of which is denoted by 6 (see Figure l). At the end portions of the rim 5 the bottom is cut away, and there the sides l of the rim 5 are pinched to grip the sandwiched portions 8 which lie between the curtain proper and the bands 2. The free ends of the bands 2 are fastened in axial slots provided at the periphery of two rollers 9 serving for the winding up of the bands, and said rollers 9 are rotationally mounted on the ends of a rotatable spindle lil adapted to rotate the rollers 9. The rotation of the spindle IB is transmitted to the rollers 9 by means of two torsional spiral springs Il encircling the spindle l0 and having the one of their ends fastened to the spindle IG and the other one to the respective roller 9.,

rfhe curtain is blackened by the application to the saine of some suitable paint.

The invention is not limited to the invention described above and shown in the accompanying drawing but may be varied in details'without departing from the spirit of it.

What I claim is:

l. An improvement in curtain shutters for cameras wherein the curtain is wound upon a rotatable support and drawn therefrom onto a second spaced rotatable support comprising a sheet of metal foil, said sheet being provided with corrugations in the form of sine-Waves extending at right angles to the direction of movement of said sheet.

2. An improvement in curtain shutters for cameras wherein the curtain is wound upon a rotatable support and drawn therefrom onto a second spaced rotatable support comprising a sheet of metal foil, a pair of spaced metal foil bands connected to an end of said sheet for attaching the same to the second of said supports. said sheet and said bands being provided with corrugations in the form of sine-waves extending at right angles to the direction of movement of said sheet and said bands.

3. An improvement in curtain shutters for cameras wherein the curtain is wound upon a rotatable support and drawn therefrom onto a second spaced rotatable support comprising a sheet of metal foil, a pair of spaced metal foil bands connected ,to an end of said sheet for attaching the same to the second of said supports, said sheet and said bands being provided with 3 4 Corrugatons in the form of sine-waves exend- UNITED STATES PATENTS ing at right angles to the direction of movement Number Name Date 0;" said snee?l and said bands and a rim mounted 835 127 Borsum NOV 6 1906 on the aforementioned end of said sheetl parallel 2 149094 Kuppenb'lEe-r Feb '28 1939 to said corrugations and forming a stiffener for 5 2309300 Brechle et al Jan' 26 1943 the shutter.

ALGOT PERCY SVENSSON. 2,446,638 Crumrme Aug. 10, 1948 FOREIGN PATENTS REFERENCES CITED Number Country Date The following references are of record n the 10 54,285 Germany Nov, 6, 1890 le of this patent: 

